Current rectifier



May 29, 1928.l L. L hf-:VY

' CURRENT REGTIFIER vFiled. Oct. 28, 1925 Fly! umm

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Patented May 29, 1928.

LUCIEN LEVY, OF PARIS, FRANCE.

CURRENT RECTIFIER.

Application led October 28, 1925. Serial No. 65,386.

This invention relates to alternating current rectifiers and has for its object an 1mproved rectifier of this kind and the application thereof, to Wireless telegraphy and o telephony and other analogous uses.

Rectifiers constituted by a strip of aluminium in contact with cuprous sulphide are already known. For one direction of the current, the aluminium becomes sulphu- IU retted and as aluminium sulphide is a nonconductor of electricity, the contact presents a very great resistance. On the 'other hand, in the reverse direction, the contact presents only a small resistance cuprous sulphide being a very good conductor. This arrangement allows large low tension currents to be easily rectified.

These devices,however, are open tothe drawback of having a poor etliciency and to fail 2U in rectifying the current'l after working for a very little time. The cause of this resides in that particles of cuprous sulphide become attached to the aluminium at certain points, and that one has then instead of an aluminium-sulphide Contact with cuprous sulphide, a cuprous sulphide contact with cuprous sulphide which does not rectify. It has been thought probable that the adherence p of the cuprous sulphide with the aluminium 3U was due to the fact that, owing to the aluminium being oxidized or undergoing oxidi- Zation under the action of the air existing between the grains of sulphide, copper aluminate, which is a conductor, Avand a sulphu retted gas, are produced.

According to this invention, I provide a rectifier or valve comprising an electric Contact between aluminium and a suitable sulphide or oxide surrounded by a sulphuretting atmosphere.

Such a valve is capable of working without interruption. Its principal feature is that the presence of air or oxide capable of affecting the aluminium is avoided by the use of a sulphuretting atmosphere surrounding the contact.

@wing to the small resistance of the conl tact between the aluminium and cuprous sulplaide in the direction of the current, it is a0 possible in this manner to heat several thermionic valve filaments 'in parallel, instead of' in series, as is necessary with electrolytic valves. This is a new result and an imporv tant improvement since the invention is henceforward applicable to the existing apparatus for wireless telephony and teleg- V raphy without any moditication whatever of this apparatus. Besides, the present rec'- titer is much more convenient to trans` port and more reliable in working than the elcctrolytic rectiliers.

Referring to the appended drawings which illustrate as an example a particular manner of carrying out this invention Fig. I represent-s in section a valve element, according` to this invention.

Fig. 2 represents a plan.

cup 1 provided with a screwed copper plug 2 and inside which is disposed an insulating circular disc 3, of bakelite for. instance, un-v der which is secured, by means of the nut 4 and of the aluminium threaded stud 5, an 4aluminium disc 6 of smaller diameter thanl the insulating disc 8. Electric connections with the plug and the cup are made by means of the .threaded stud 8 screwed on the said plug and provided with nuts 9, and by means of thestud 5 provided with the nuts 4, respectively.

A suitable compound 7 adapted to con-v stitute with aluminium a rectifying Contact is compressed between the disc 3 and the `lu 2. VThis compound which is a copper salt is obtained as follows:

Copper sulphide is first obtained under a suitable form. To this end, the copper and the sulphur are heated in 'approximately molecular proportions in a glass ask, there being, however, a slight excess of sulphur in order to ensure the complete transformation of the copper to sulphide; the sulphide is then ground in a mortar so as to constitute a powder the grains 'of which are of the order of 0.2 millimetres in diameter; this powder 1s passed through a sieve so as to eliminate any particle of metallic copper. The

essential feature of the invention resides in that this powder is made into a paste by mixing it with a liquid which maybe either a mineral or Vegetable oil or a suitable liquid organic compound, preferably a sulphuretting liquid, sucho as sulpho-hydrate of ammonia or a solution of sodium sulphide.

This paste is introduced between the aluminium disc 6 and the copper lug 2 and is strongly compressed between tlgem Y' The aluminium surface itself must be subjected to a special treatment which consists in a very careful polishing of the face'and of the edge in `contact with the sulphide.

The apparatus 1s constituted by a copper This polishing must preferably be performed immediately before the assembling of the valve, in order to avoid the oxidation of the aluminium.

The apparatus must be so constructed as to be as tight, so that a gaseous Apressure caused y the vaporization of the sulphuretting liquid may be produced inside theap- -under pressure, for instance sulphuretted hydro en. i

T e arrangement so constructed constitutes a valve permitting one to easily rectify large currents atv low voltages, and which will be much more convenient to use in practice than valves containing a liquid.

It is also possible to apply the above described device to constiauct a condenser by making the two electrodes of aluminium by replacing for instance the copper pieces l and 2 o f Fig. 1 by pieces of aluminium. The condensers so obtained may be used in wireless telegraphy or telephony to establish low tension filters in'combination with rectiers of the kind described.

What I claim and desire to secure by Lets l ters Patent of the United States is:

1. A `current rectifier comprising a copper plug screwed in a copper cylinder constituting an electrode, a nonconducting element forming the cylinder bottom, an aluminium electrode xed upon said nonconducting cylinder bottom, a paste'consisting of a sulphide moistened with a sulphuretting liquid capable of producing a sulphuretting atmosphere and means to compress the paste between the two electrodes;

2.- A current rectifier comprlsing a copper cup, a copper plug screwed in 'saidl cup and constituting an electrode, a non'conducting y compressed between the'- two electrodes' and including means to produce a sulpliurettlng atmosphere.

4. A current rectifier comprising a copper cup, a copper plug screwed in said cup and forming an electrode, means to lfix said electrode-plugto a current lea'd, a nonconducting .element forming4 the cup bottom, a gas tight joint between said nonconducting bottom andthe cup, an aluminium electrode lixed upon said non conducting cup bottom, means to fix another current lead to said aluminium electrode, and a metal sulphide mixed with a' sulpliuretting compound coni-A pressed between the two electrodes.

5. A current rectifier comprising an aluminium electrode and acopper electrode in combination with a Iconducting i sulphide mixed with a sulphuretting liquid compressed between the electrodes.

In testimony 'that I claim the foregoing as my invention, I'have signed my name.

LUCIEN LEVY'. 1 

